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84 lines
2.5 KiB
C
84 lines
2.5 KiB
C
/* Copyright (C) 2003-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <endian.h>
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#include <errno.h>
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#include <sysdep.h>
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#include <lowlevellock.h>
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#include <pthread.h>
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#include <pthreadP.h>
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#include <shlib-compat.h>
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#include <kernel-features.h>
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#include <stap-probe.h>
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int
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__pthread_cond_signal (pthread_cond_t *cond)
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{
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int pshared = (cond->__data.__mutex == (void *) ~0l)
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? LLL_SHARED : LLL_PRIVATE;
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LIBC_PROBE (cond_signal, 1, cond);
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/* Make sure we are alone. */
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lll_lock (cond->__data.__lock, pshared);
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/* Are there any waiters to be woken? */
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if (cond->__data.__total_seq > cond->__data.__wakeup_seq)
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{
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/* Yes. Mark one of them as woken. */
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++cond->__data.__wakeup_seq;
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++cond->__data.__futex;
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#if (defined lll_futex_cmp_requeue_pi \
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&& defined __ASSUME_REQUEUE_PI)
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pthread_mutex_t *mut = cond->__data.__mutex;
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if (USE_REQUEUE_PI (mut)
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/* This can only really fail with a ENOSYS, since nobody can modify
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futex while we have the cond_lock. */
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&& lll_futex_cmp_requeue_pi (&cond->__data.__futex, 1, 0,
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&mut->__data.__lock,
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cond->__data.__futex, pshared) == 0)
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{
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lll_unlock (cond->__data.__lock, pshared);
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return 0;
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}
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else
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#endif
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/* Wake one. */
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if (! __builtin_expect (lll_futex_wake_unlock (&cond->__data.__futex,
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1, 1,
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&cond->__data.__lock,
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pshared), 0))
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return 0;
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/* Fallback if neither of them work. */
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lll_futex_wake (&cond->__data.__futex, 1, pshared);
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}
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/* We are done. */
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lll_unlock (cond->__data.__lock, pshared);
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return 0;
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}
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versioned_symbol (libpthread, __pthread_cond_signal, pthread_cond_signal,
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GLIBC_2_3_2);
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